It has long been desired to maximize fuel economy, power and driveability in vehicles while enhancing acceleration, reducing emissions, and preventing hesitation. Both gasoline and diesel powered engines use dispersants to keep fuel delivering systems, such as filters and injectors, clean. However, gasoline engines and diesel engines may require different types of detergents for such purposes. The reasons for this unpredictability lie in the many differences between the fuel compositions that are suitable for such engines.
Additionally, new engine technologies require more effective additives to keep the engines running smoothly. Additives are required to keep the fuel injectors clean or clean up fouled injectors for spark-ignited and compression-ignited engines. Engines are also being designed to run on alternative renewable fuels. Such renewal fuels may include fatty acid esters and other biofuels which are known to cause deposit formation in the fuel supply systems for the engines. Such deposits may reduce or completely block fuel flow, leading to undesirable engine performance.
Also, low sulfur fuels and ultra low sulfur fuels are now common in the marketplace for internal combustion engines. A “low sulfur” fuel means a fuel having a sulfur content of 50 ppm by weight or less based on a total weight of the fuel. An “ultra low sulfur” fuel means a fuel having a sulfur content of 15 ppm by weight or less based on a total weight of the fuel. Low sulfur fuels tend to form more deposits in engines than conventional fuels, for example, because of the need for additional friction modifiers and/or corrosion inhibitors in the low sulfur fuels.
Quaternary ammonium compounds are known detergents suitable for cleaning up deposits in engines. However, the manufacturing process for such quaternary ammonium salts may be difficult and the performance of the quaternary ammonium salts may still need improvement. For example, removing undesirable ash generating components from the manufacturing process for internal quaternary ammonium salts is complicated. Furthermore, conventional quaternary ammonium salts may not be sufficiently effective for improving injector performance at relatively low treat rates. In addition, certain quaternary ammonium compounds have high HLB values and are thus are highly water soluble which causes such compounds to separate out in hydrocarbon fuels. Accordingly, there continues to be a need for fuel additives that are highly effective in cleaning up fuel injector or supply systems and maintaining the fuel injectors operating at their peak efficiency and that do not contain ash generating elements or separate out in fuels or fuel additive packages.
In accordance with the disclosure, exemplary embodiments provide a synergistic fuel additive concentrate for use in fuel injected engines, a method for cleaning fuel injectors for an internal combustion engine, a method for restoring power to a fuel injected engine, a fuel composition, a method for improving performance of fuel injectors, and a method of operating a fuel injected diesel engine. The additive concentrate includes a mixture of (a) an alkoxylated quaternary ammonium salt of the formula (R1)nN[(R2O)xH]m, wherein R1 comprises an alkyl group having from 1 to 25 carbon atoms, R2 comprises an alkyl group having from 1 to 4 carbon atoms, n and m are each integers from 1 to 3, provided n+m=4, and at least one R1 has at least 8 carbon atoms, and x is an integer ranging from 1 to 5; and (b) a hydrocarbyl compound containing a hydrogen-bonding group other than an alkyl hydroxyl group selected from the group consisting of a hydrocarbyl acid; hydrocarbyl polyacid; hydrocarbyl substituted hydroxybenzene; hydrocarbyl substituted succinic diamide, acid/amide, diacid, diester, ester/acid, amide/ester, imide; aminotriazole, and mixtures thereof, wherein the hydrocarbyl substituent has a number average molecular weight of from about 100 to about 1500, and wherein a weight ratio of (a) to (b) in the additive mixture ranges from about 1:5 to about 1:1.
Another embodiment of the disclosure provides a method of improving the injector performance of a fuel injected engine. The method includes operating the engine on a fuel composition that includes a major amount of fuel and from about 5 to about 100 ppm by weight based on a total weight of the fuel of a synergistic fuel additive. The synergistic fuel additive includes a mixture of (a) an alkoxylated quaternary ammonium salt of the formula (R1)nN[(R2O)xH]m, wherein R1 comprises an alkyl group having from 1 to 25 carbon atoms, R2 comprises an alkyl group having from 1 to 4 carbon atoms, n and m are each integers from 1 to 3, provided n+m=4, and at least one R1 has at least 8 carbon atoms, and x is an integer ranging from 1 to 5; and (b) a hydrocarbyl compound containing a hydrogen-bonding group other than an alkyl hydroxyl group selected from the group consisting of a hydrocarbyl acid; hydrocarbyl polyacid; hydrocarbyl substituted hydroxybenzene; hydrocarbyl substituted succinic diamide, acid/amide, amide/ester, diacid, diester, ester/acid, imide; aminotriazole, and mixtures thereof, wherein the hydrocarbyl substituent has a number average molecular weight of from about 100 to about 1500, and wherein a weight ratio of (a) to (b) in the additive mixture ranges from about 1:5 to about 1:1 and wherein when the synergistic additive(s) is present in the fuel, at least about 60% of the power lost during a dirty up phase of a CEC F98-08 test conducted in the absence of the synergistic additive(s) is recovered.
A further embodiment of the disclosure provides a method of operating a fuel injected engine. The method includes combusting in the engine a fuel composition containing a major amount of fuel and from about 5 to about 100 ppm by weight based on a total weight of the fuel of a synergistic fuel additive. The synergistic fuel additive includes (a) an alkoxylated quaternary ammonium salt of the formula (R1)nN[(R2O)xH]m, wherein R1 comprises an alkyl group having from 1 to 25 carbon atoms, R2 comprises an alkyl group having from 1 to 4 carbon atoms, n and m are each integers from 1 to 3, provided n+m=4, and at least one R1 has at least 8 carbon atoms, and x is an integer ranging from 1 to 5; and (b) a material containing a hydrogen-bonding group other than an alkyl hydroxyl group selected from the group consisting of a hydrocarbyl acid; hydrocarbyl polyacid; hydrocarbyl substituted hydroxybenzene; hydrocarbyl substituted succinic diamide, acid/amide, amide/ester, diacid, diester, ester/acid, imide; aminotriazole, and mixtures thereof, wherein the hydrocarbyl substituent has a number average molecular weight of from about 100 to about 1500, and wherein a weight ratio of (a) to (b) in the additive mixture ranges from about 1:5 to about 1:1.
An advantage of the fuel additive described herein is that the additive may not only reduce the amount of deposits forming on fuel injectors, but the additive may also be effective to clean up dirty fuel injectors sufficient to provide improved power recovery to the engine. The combination of components (a) and (b) in a fuel may be synergistically more effective for improving injector performance and power recovery (power restoration) than each of the components (a) and (b) alone in the fuel. Likewise, the synergistic mixture of components (a) and (b) may be more effective in minimizing deposit formation and in cleaning up injector deposits in indirect injected as well as direct injected engines than each of the components used separately.
Additional embodiments and advantages of the disclosure will be set forth in part in the detailed description which follows, and/or can be learned by practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.